MySQL Articles

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MySQL query to fetch records before currentdate + 2 weeks?

AmitDiwan
AmitDiwan
Updated on 16-Dec-2019 823 Views

For this, use the below syntax −select * from yourTableName where yourColumnName < DATE_ADD(CURDATE(), INTERVAL 2 WEEK);Note: The current date is as follows −mysql> select curdate(); +------------+ | curdate()  | +------------+ | 2019-10-20 | +------------+ 1 row in set (0.00 sec)Let us first create a table −mysql> create table DemoTable1607    -> (    -> ShippingDate date    -> )    -> ; Query OK, 0 rows affected (0.58 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1607 values('2019-10-20'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1607 values('2019-11-04'); Query OK, 1 row affected ...

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Implement Harmonic mean and Quadratic mean in MySQL?

AmitDiwan
AmitDiwan
Updated on 16-Dec-2019 178 Views

Let us first create a table −mysql> create table DemoTable1606    -> (    -> Value int    -> ); Query OK, 0 rows affected (0.55 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1606 values(5); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1606 values(10); Query OK, 1 row affected (0.12 sec)Display all records from the table using select statement −mysql> select * from DemoTable1606;This will produce the following output −+-------+ | Value | +-------+ |     5 | |    10 | +-------+ 2 rows in set (0.00 sec)Here is the ...

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MySQL update column to NULL for blank values

AmitDiwan
AmitDiwan
Updated on 16-Dec-2019 3K+ Views

For this, you can use IF() along with UPDATE command. Let us first create a table −mysql> create table DemoTable1601    -> (    -> FirstName varchar(20) ,    -> LastName varchar(20)    -> ); Query OK, 0 rows affected (0.53 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1601 values('John', 'Doe'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1601 values('Adam', ''); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable1601 values('David', 'Miller'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable1601 values('Chris', ''); Query OK, 1 row affected ...

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Using UNIQUE for varchar columns with some conditions in MySQL?

AmitDiwan
AmitDiwan
Updated on 16-Dec-2019 252 Views

For this, you can use UNIQUE constraint on one or more columns −alter table yourTablleName add unique(yourColumnName1, yourColumnName2, ...N);Let us first create a table −mysql> create table DemoTable1598    -> (    -> EmployeeId int,    -> EmployeeName varchar(20),    -> EmployeeCountryName varchar(20)    -> ); Query OK, 0 rows affected (0.52 sec)Here is the query to implement UNIQUE on varchar columns −mysql> alter table DemoTable1598 add unique(EmployeeName, EmployeeCountryName); Query OK, 0 rows affected (0.55 sec) Records: 0  Duplicates: 0  Warnings: 0Insert some records in the table using insert command −mysql> insert into DemoTable1598 values(101, 'Adam', 'AUS'); Query OK, 1 ...

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Fix ERROR 1093 (HY000): You can't specify target table for update in FROM clause while deleting the lowest value from a MySQL column?

AmitDiwan
AmitDiwan
Updated on 16-Dec-2019 1K+ Views

Let us first create a table −mysql> create table DemoTable1597    -> (    -> Marks int    -> ); Query OK, 0 rows affected (0.69 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1597 values(45); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable1597 values(59); Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable1597 values(43); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable1597 values(85); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1597 values(89); Query OK, 1 row affected (0.12 sec)Display all records from the table ...

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Can we use "rank" as column name with MySQL8?

AmitDiwan
AmitDiwan
Updated on 16-Dec-2019 4K+ Views

The rank is a MySQL reserved word defined in MySQL version 8.0.2. Therefore, you cannot use rank as a column name. You need to use backticks around the rank.Let us first check the MySQL version we are working on. Here, I am using MySQL version 8.0.12 −mysql> select version(); +-----------+ | version() | +-----------+ | 8.0.12    | +-----------+ 1 row in set (0.00 sec)The issues by using “rank” as column name are as follows −mysql> create table DemoTable1596    -> (    -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    -> StudentName varchar(20),    -> rank int   ...

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MySQL RegExp to fetch records with only a specific number of words

AmitDiwan
AmitDiwan
Updated on 16-Dec-2019 225 Views

For this, use Regular Expression in MySQL as in the below syntax −select * from yourTableName where yourColumnName regexp '\land[\land ]+[ ]+[\land ]+$';The above query will work when the two words are separated by a space. Let us first create a table −mysql> create table DemoTable1412    -> (    -> Name varchar(40)    -> ); Query OK, 0 rows affected (0.52 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1412 values('John Adam Carol'); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable1412 values('Mike Sam'); Query OK, 1 row affected (0.15 sec) mysql> insert ...

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Call Stored Procedures within a Stored Procedure with IF Logic?

AmitDiwan
AmitDiwan
Updated on 16-Dec-2019 750 Views

To call stored procedures within a stored procedure, the syntax is as follows −If yourInputValue > 100 then      call yourProcedureName1();  else     call yourProcedureName2();     end If ;     ENDLet us implement the above syntax. In order to implement the above concept, let us create a stored procedure −mysql> delimiter // mysql> create procedure Hello_Stored_Procedure()    -> BEGIN    -> select 'Hello World!!!';    -> END    -> // Query OK, 0 rows affected (0.18 sec)The query to create the second stored procedure is as follows −mysql> create procedure Hi_Stored_Procedure()    -> BEGIN    -> ...

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Alternative to MySQL CASE WHEN in MySQL

AmitDiwan
AmitDiwan
Updated on 16-Dec-2019 771 Views

Use IF() method as an alternative to CASE WHEN in MySQL. Let us first create a table −mysql> create table DemoTable1593    -> (    -> PlayerScore int    -> ); Query OK, 0 rows affected (0.44 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1593 values(78); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable1593 values(0); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable1593 values(89); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1593 values(0); Query OK, 1 row affected (0.16 sec)Display all records from the table using ...

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How to convert varchar "time" to real time in MySQL?

AmitDiwan
AmitDiwan
Updated on 16-Dec-2019 557 Views

For this, you can use TIME_FORMAT(). Let us first create a table −mysql> create table DemoTable1591    -> (    -> ArrivalTime varchar(20)    -> ); Query OK, 0 rows affected (0.58 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1591 values('1620'); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable1591 values('2345'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable1591 values('2210'); Query OK, 1 row affected (0.12 sec)Display all records from the table using select statement −mysql> select * from DemoTable1591;This will produce the following output −+-------------+ | ArrivalTime | +-------------+ ...

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